Learning Performances:

• Define a species and give examples
• Define a population and identify local populations
• Explain how extinction removes genes from the gene pool
• Explain the importance of the fossil record

• Summarize the major concepts of natural selection
• Describe how natural selection provides a mechanism for evolution
• Explain how a new species or variety may originate through the evolutionary process of natural selection.
• Explain how natural selection leads to organisms that are well suited for the environment.
• Explain, using examples, how the fossil record, comparative anatomy, and other evidence may support the theory of evolution.

• Describe species as reproductively distinct groups of organisms that can be classified based on morphological, behavioral, and molecular similarities.

• Explain how natural selection acts on individuals, but it is populations that evolve. Relate genetic mutations and genetic variety produced by sexual reproduction to diversity within a given population.
• Describe the role of geographic isolation in speciation.
• Give examples of ways in which genetic variation and environmental factors are causes of evolution and the diversity of organisms.
• Explain how evolution through natural selection can result in changes in biodiversity.
• Explain how changes at the gene level are the foundation for changes in populations and eventually the formation of new species.

Standards:

By the end of the 12th grade, students should know that

• The basic idea of biological evolution is that the earth's present-day species developed from earlier, distinctly different species.
• Molecular evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from one another.
• Natural selection provides the following mechanism for evolution: Some variation in heritable characteristics exists within every species, some of these characteristics give individuals an advantage over others in surviving and reproducing, and the advantaged offspring, in turn, are more likely than others to survive and reproduce. The proportion of individuals that have advantageous characteristics will increase.
• Heritable characteristics can be observed at molecular and whole-organism levels-in structure, chemistry, or behavior. These characteristics strongly influence what capabilities an organism will have and how it will react, and therefore influence how likely it is to survive and reproduce.
• New heritable characteristics can result from new combinations of existing genes or from mutations of genes in reproductive cells. Changes in other cells of an organism cannot be passed on to the next generation.
• Natural selection leads to organisms that are well suited for survival in particular environments. Chance alone can result in the persistence of some heritable characteristics having no survival or reproductive advantage or disadvantage for the organism. When an environment changes, the survival value of some inherited characteristics may change.
• The theory of natural selection provides a scientific explanation for the history of life on earth as depicted in the fossil record and in the similarities evident within the diversity of existing organisms.
• Life on earth is thought to have begun as simple, one-celled organisms about 4 billion years ago. During the first 2 billion years, only single-cell microorganisms existed, but once cells with nuclei developed about a billion years ago, increasingly complex multicellular organisms evolved.
• Evolution builds on what already exists, so the more variety there is, the more there can be in the future. But evolution does not necessitate long-term progress in some set direction. Evolutionary changes appear to be like the growth of a bush: Some branches survive from the beginning with little or no change, many die out altogether, and others branch repeatedly, sometimes giving rise to more complex organisms.